Anti-pump control circuit for motor closed circuit breaker



Aprxl 3, 1962 F. J. PoKoRNY ETAL 3,028,527

ANTI-PUMP CONTROL CIRCUIT FOR MOTOR CLOSED CIRCUIT BREAKER Filed March 17, 1958 3 Sheets-Sheet l April 3, 1962 J. POKORNY ET AL ANTI-PUMP CONTROL CIRCUIT FOR MOTOR CLOSED CIRCUIT BREAKER Filed March 17, 1958 3 Sheets-Sheet 2 April -3, 1962 F. J. PoKoRNY ET AL 3,028,527

ANTI-PUMP CONTROL CIRCUIT FOR MOTOR CLOSED CIRCUIT BREAKRR Filed March 17, 1958 5 Sheets-Sheet 3 tl :515C

M Arrm//Eyf 3,028,527 Patented Apr. 3, `1962 3,028,527 ANTI-PUMP CONTROL CIRCUIT FOR MOTOR CLOSED CIRCUIT BREAKER Frank J. Pokorny, Hatboro, Pa., and Challiss I. Clausing, Collingswood, NJ., assignors to I-T-E Circuit B reaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Mar. 17, 1958, SerrNo. 721,971 8 Claims. (Cl. 317-54) The instant invention relates to an electric closing circuit for circuit breakers which have extremely fast opening characteristics and which are closed by motor operation.

In our copending application Serial No. 660,982, tiled May 22, 1957, now Patent No. 2,939,930, assigned to the assignee ofthe instant invention and entitled, ,Motor Closing Mechanism for Circuit Breakers, there is described a high speed circuit breaker and a motor closing mechanism therefor. The circuit breaker includes an over-center toggle system whichis utilized as the output of the motor mechanism, this toggle system forming a latch for the circuit breaker contacts when they are driven to their engaged position. In prior art closing arrangements the motor is allowed to coastV after its deenergization, resulting in a tendency of the toggle mechanism to rebound after reaching the intended stop position and on occasion the toggle mechanism has been known to rebound passed dead center resulting in a highly undesirable slow opening operation of the circuit breaker contacts.

The instant invention provides a control arrangement whereby resistance is inserted in series with the closing motor when the toggle mechanism passes over center causing themotor to stall in the closed position of the o circuit breaker with approximately IAO normal voltage on the motor. The reduced voltage together with the inertia of the. moving parts insures that the toggle will remain over center against its stop without rebounding. During closing, the circuit breaker movable contact may operate independently of the toggle linkage through a trip free mechanism and after trip free operation the toggle linkage is reset with a time delay which is provided by the resistance of the closing motor and the output gearing which provides the operative connection between the motor and the toggle mechanism. Once the mechanismL is reset energization of the motor will once again achieve a closing operation of the circuit breaker.

Briey, the circuit arrangement of the instant invention includes a control relay which is energized by the closing initiating switch and when so energized closes` a iirst and a second pair of cooperating contacts which energize the closing motor and at the same time bypass the closing initiating switch thus sealing the relay in the circuit through its own contact. When the toggle mechanism reaches its over center position, a third pair of contacts instantaneously opens thereby placing a resistance in series with the motor so that the torque thereof is sub-` santially reduced. A four pair of normally closed contacts, having delayed opening characteristics, are also operated by the passing of the toggle mechanism over the center position. The fourth pair of contacts is connected in series between the'control relay and the iirst pair of contacts thereby enabling the first pair of contacts to bypass the closing initiating switch. However, when the fourthpair of contacts open the energizing circuit to the control relay the irst pair of contacts will be opened so that the first pair of now open contacts thereby interrupts the energizing circuit to the motor.

Instantaneous trip control is provided by a normally closed switch which is connected in series between the polarizing coil of the magnetic latch and its energizingsource.

Accordingly, a primary object of the instant invention is to provide a novel anti-pump control scheme for a high speed motor operated circuit breaker.

Another object is to provide a novel anti-pump control arrangement which requires fewer components than con-V trol arrangements of the prior art.

`Still another object is to provide a novel anti-pump control arrangement which insures but a single closing p attempt per operation of the closing control switch.

A further object is to provide a novel anti-pump control arrangement which includes a sealing in control so that the circuitbreaker closes independently of the closing control switch.

A still further object is to provide a novel anti-pump control arrangement which achieves positive over-center positioning of the circuit breaker operating toggle mechanism without the danger of rebounding.

These as well as other objects of the instant invention shall become readily apparent after reading the following description ofthe accompanying drawings in which:

FIGURE l is a combined electrical and mechanical schematic of a circuit breaker having an anti-pump control arrangement constructed in accordance with the teachings of the instant invention.

FIGURE 2A is a wiring diagram of our novel antipump control arrangement.

FIGURE 2B is a simplified wiring schematic diagram of the circuit illustrated in FIGURE 1.

IFIGURES 3, 4 and 5 are schematic diagrams illustrating a circuit breaker which is to be operated by our novel anti-pump control arrangement. In FIGURE 3 the circuit breaker is closed. -In FIGURE 4 the circuit breaker is trippedropen. In FIGURE 5 the circuit breaker is reset.

Referring to the figures, FIGURES 3-5 illustrate schematically the circuit breaker mechanism fully described in our aforesaid application Serial No. 660,982. Since this circuit breaker mechanism merely serves as a setting for our invention, the following description of the mechanism has been reduced to the bare essentials.

In FIGURE 3 the high speed circuit breaker 10 is closed, with movable contact 11 being in engagement with stationary contact 1,2. Spring 13 exerts a direct acting opening force but the breaker 10 is yheld closed by the magnetic latch comprising armature 14 which is secured to magnet 15 by a flux generated by polarizing coil 16. The magnet structure K15, which is otherwise free to pivot about point 17, is now held by the overcenter toggle, comprising links 18, 19 whose knee 20 bears against stop 21.

This toggle condition is maintained by the clockwise component of force produced by the opening spring 13 and transmitted through the armature 14 which is sealed to the magnet structure 15. In a breaker set for high speed reverse current trip the flux produced by a forward current in bucking bar 22 aids the flux produced by polarizing coil 16 and helps to hold armature 14 against the magnet 15. When the main current reverses, the bucking bar ux also reverses and reduces the flux through the armature 14 by shifting flux through air gap 23 into the alternate path; The armature 14 is now free and is parted from the magnet 15 by the opening spring 13 thus removing the force of spring 13 from the toggle 18, 19. After the breaker contacts 11, 12 open, tension spring 25 acts on link 18 to breaky the toggle 18, 19, 20 thereby allowing the magnet structure 15 to pivot downward about point 17. The breaker 10 is now in the fully open position as shown in FIGURE 5.

When the breaker 10 is set for high speed tripping spaans? ture path. When the current in the breaker liti and bucking bar 22 rises to a predetermined value, the armature flux is reduced to a value which allows the breaker it@ to open in the same manner as outlined above.

The closing operation begins by closing the control circuit to motor 26 which drives link 13 through a spring clutch (not shown) until the over-center toggle condition is re-established. When thev knee 2.@ touches stop 2li, the spring clutch disengages the motor 2.6, and the motor control circuit is opened by limit switch contacts operated by the toggle members l, 19,. Duringthisclosing operation, the armature 14 is `sealed tothe magnet i5 by the polarizing flux. It adverse conditions still exist on the main Circuit, the breaker is free to trip (FIGURE Ll) even though the motor 26 is driving the magnet struc ture 15 toward the closed position. Manual closing is performed by means of a removable handle (not shown)v on the motor shaft. Thus., the circuit breaker is` mechanically and electrically trip-free.

' Now referring more particuliarly to FIGURES l and 2, our novel anti-pump control scheme comprises three series. paths connected in parallel across lines 3i, 32

which are connected to the positive and negative terminals respectively of D.C. power source 30. The first series path comprises the closingrelay coil 33 and normally open closing switch 34.

The second path comprises in order a iirst pair of normally open contacts 35, operating motor 26, a, variable resistor 37, and a second pair of normally open contacts 36. A pair ofnormally closed contacts 33, associlated with the toggle membersl, 19` is connected across resistor 37 and a pair of normally closed and slow to open contacts 4t), also associated with the toggle members, 1,8, 19 is connected between the junction of closing switch 34 and closing coil 33 and the junction of resistor of trip control '41 interrupts the energizing circuit to` polarizing coil 16 thereby reducing the flux in magnet structure 15 so thatarmature 14 is separated therefrom and cooperating contacts lll and 12 are parted by spring 13. Thus circuit breaker 10 may he tripped regardless of the position of the operating mechanism therefor.

`Closing of circuit breaker 10 from the reset position of FGURE 5 is initiated by operating closing switch 34. This energizes coil 33 of the closing relay which closes thev pairsV of contacts 35, 36 in series" with motor 26. Closed contactsV 36 and normally closed contacts 40 pro# vide anA energizing path for coil 33 which is independent of closing switch 34.

Since resistor 37 is shortedi by contacts 38 motor 26 is now connected directly to power source 33. Motor 26 begins;` to rotate and moves link i8 to the right therebyI straightening toggle 13, 19 so that magnet 15 isl rotated about point 17 causing movable contact 111:0 approach stationaryy contact 12. When toggle 18, 19 goes over-r center knee 2-0 engages stop 21 andl contacts 38 are opened thereby placing resistor 37 in series with motor 26;l This reduces the motor voltage to approximatelyy of normal as determined: bythe resistance value ofvari ableresistor 37. The reduced voltage applied to motor 26 tending 'tov move knee 20 against stop 2., together with the inertiaof the moving parts, prevents any rebound of toggle 18,v 19.

Contacts 40 may be ganged to contacts 38 but mechanically set toY open` a short time thereafter. Alternately contacts 40 may be operated open by a sequence arrangement. ln any event, opening of contacts 4d follows the opening, ofY contacts 38. Opening of contacts 40 interrupts the holding circuit for operating'coil 33A which is thereby deenergized unless closing initiating switch 34 remains closed.

If breaker l@ closes on a fault or if for any reasonV magnetic latch 14, l5 releases during closing, breaker 1t) trips independently of toggle i3, 19. Motor 26 continues to operate toggle 18, 19 tothe over-center position of FIGURE 4. However, spring 25 cannot collapse toggle 18, i9 while closing switch 34 isl closed since even the reduced voltage to motor 26 prevents a backward rota4 tion thereof. This assures. but a singleV closing attempt per operation of switch 34. l

Even though control voltage source 3&3 is'the same source being protectedV by circuit breaker 10, pumping will not result. If the voltage dips. due to breaker 10 closing' on a fault and interrupting a fault, ay resetting action" may start.A However, there is a considerable intentional time delay in resetting the magnet l5 and voltage will be restored before armature )i4 can. be resealed' or latched to magnetl 15.

While our novel circuitry has been described utilizing a motor as the circuit breaker operating means, it should be readily understood that the principlesk of "this invention may readily be utilized for solenoid operated circuit break ers. Further, it is possible that any combination of thc three series paths may be energized from separate voltage sources. Assuming that the iirst and second series paths are operated from separate voltage sources, then contacts 40 are replaced by a dropout time delay which must be built into closing relay 33 so that a complete closing cycle would take `place before relay dropout. In the alternative contact 40 may be isolated from the second' series path and placed, in seriesk with a set of normally open contacts gauged to` closing relay contacts 36. The series` combination of contact 40 and the set of open contacts'is con'- nected across closing switch 34. p

It is also to be understood that the source` and/orcom trol voltages may be either A.C`. or D.C`. However, if theV voltage applied to the third series path is A.C. then a rectier is required in series with polarizing coil 16.

Thus we have provided a novel anti-pump controlar rangement which provides positive protection regardless of momentary control voltage dips; Dur circuit results in the elimination of the relay holding coil associated with closing coils of prior art circuitry and furthereliminates service. Advantages are gained in continuity of service and maintenance` since; control wiring is simplified' and fewer parts result in a reduced likelihood of mis'- operation and failure. v V

Although we have here described preferred embodifment of our novel invention, many variations and modications will now be apparent to those skilled in' the art,

and we therefore preferto-be limited,y not by the specific disclosure herein, butY only by the appending claims.

We claim:Y

l. An electrical control circuit for a mot-or closedhigh speed circuit breaker comprising a firsty and a second circuit connected in parallel; said' firsty circuit including a normally open switch and a relay coil connected in electrical series; said second circuit including a iirstv normally open contact and a circuit breaker closing meansc'onnected in electrical series; said closing means being'constructedftoA ond normallyA closed contact'being opened by operation of saidl toggle operating mechanism over-center` as said circuit breaker'is operated from an open toa closed-position;- said secondcircuit also including a resistor connectedA in electrical series with saidL circuit breaker closing'means; a third normally closedcontact connected ine'parallel with said resistor; saidthird contact also beingoperativelypositioned to be opened by said mechanism when said mechanism is operated to a predetermined position as said circuit breaker is being closed.

2. An electrical control circuit for a motor closed high speed circuit breaker comprising a first and a second circuit connected in parallel; said first circuit including a normally open switch and a relay coil connected in electrical series; said second circuit including a first normally open contact and a circuit breaker closing motor connected in electrical series; said motor being adapted to provide motive power for physical movement of circuit breaker contacts; said first contact being closed by the energizetion of said relay coil; a second normally closed contact being electricallyvconnected between said switch and said first contact; said first andisaid second contacts comprising a by-pass circuit for said switch; said circuit breaker includng a toggle operating mechanism; said second contact being opened when said toggle operating mechanism is moved over-center as saidA circuit breaker is operated from an open to a closed-position; said second circuit also including a resistor connected in electrical series with said motor; a third normally closed Acontact also being operatively positioned VVto vbe opened by saidVV mechanism rwhen said mechanism is operated to a predetermined position as said circuit breaker is being closed; said third contact being opened before said second contact is open.

3. An electrical control circuit for a motor closed high speed circuit breaker comprising a first and a second circuit connected in parallel; said first circuit including a normally open switch and a relay coil connected in electrical series; said second circuit including a first normally open contact and a circuit breaker closing motor connected in electrical series; said motor being adapted to provide motive power for physical movement of circuit breaker contacts; said first contact being closed by the energization of said relay coil; a second normally closed contact being electrically connected between said switch and said first contact; said first and said second contacts comprising a by-pass circuit for said switch; said circuit breaker including a toggle operating mechanism; said second contact being opened when said toggle operating mechanism is moved over-center as said circuit breaker is operated from an open to a closed position; said Second circuit also including a resistor connected in electrical series with said motor; a third normally closed contact also being operatively positioned to be opened by said mechanism when said mechanism is operated to a predetermined position as said circuit breaker is being closed; said third contact being opened before said second contact is open; a third circuit connected in parallel with said first and said second circuit; said third circuit comprising a normally closed switch and a coil means connected in electrical series; said coil means being part ota trip means for said circuit breaker.V

4. An electrical control circuit for a motor closed high speed circuit breaker comprising a first and a second circuit connected in parallel; said first circuit including a normally open switch and a relay coil connected in electrical series; said second circuit including a first normally open contact and a circuit breaker closing motor connected in electrical series; said motor being adapted to provide motive power for physical movement of circuit breaker contacts; said first contact being closed by the Y energization of said relay coil; a second normally closed contact being electrically connected between said switch and said first contact; said first and said second contacts comprising a by-pass circuit for said switch; said circuit breaker including a toggle operating mechanism; said second contact being opened when said toggle operating mechanism is moved over-center as said circuit breaker is operated from an open to a closed position; said second circuit also including a resistor connected in electrical series with said motor; a third normally closed contact also being operatively positioned to be opened by said mechanism when said mechanism is operated to a predetermined position as said circuit breaker is being closed; said third contact being opened before said second con tact is open; a third circuit connected in parallel with said first and said second circuit; said third circuit comprising a normally closed switch and a coil means connected in electrical series; said coil means being part of a trip means for said circuit breaker; said controll circuit being adapted for connection to the same electrical power source being protected by said circuit breaker.

5. An electrical control circuit for a motor closed high speed circuit breaker comprising a first and a second circuit connected in parallel; said first circuit including a normally open switch and a relay coil connected in electrical series; said second circuit including a first normally open contact and a circuit breaker closing motor connected in electrical series; said motor being adapted to provide motive power for. physical movement of circuit breaker contacts; said first contact being closed by the energization of said relay coil; a second normally closed contact being electrically connected between said switch and said first contact; said first and said second contacts comprising a by-pass circuit for said switch; said circuit breaker including a toggle operating mechanism; said second contact being opened when said'toggle operating mechanism is moved over-center as said circuit breaker is operated from an open to a closed position; said second circuit also including a resistor connected in electrical series with said motor; a third normally closed contact connected in parallel with said resistor; said third contact also being opened when said toggle operating mechanism is moved over-center as said circuit breaker is operated from said open to said closed positions.

6. An electrical control circuit for a motor closed high speed circuit breaker comprising a first and a second circuit connected in parallel; said first circuit including a normally open switch and a relay-coil connected in electrical series; said second circuit including a first normally open contact and a circiut breaker closing motor connected in electrical series; said motor being adapted to provide motive power for physical movement of circuit breaker contacts; said first contact being closed by the energization of said relay coil; a second normally closed contact being electrically connected between said switch and said first contact; said first and said second contacts comprising a by-pass circuit for said switch; said circuit breaker including a toggle operating mechanism; said second contact being opened when said toggle operating mechanism is moved over-center as said circuit breaker is operated from an open to a closed position; said second circuit also including a resistor connected in electrical series with said motor; a third normally closed contact connected in parallel with said resistor; said third contact also being opened when toggle operating mechanism is moved over-center as said circuit breaker is operated from said open to said closed positions; said third contact being opened before said second contact is open.

7. An electrical control circuit `for a motor closed high speed circuit breaker comprising a first and a second circuit connected in parallel; said first circuit including a normally open switch and a relay coil connected in electrical series; said second circuit including a first nor- `mally open contact and a circuit breaker closing motor connected in electrical series; said lmotor being adapted to provide motive power for physical movement of circuit breaker contacts; said first contact being closed by the energization of said relay coil; a second normally closed contact being electrically connected between said switch and said first contact; said first and said second contacts comprising a by-pass circuit for said switch; said circuit lbreaker including a toggle operating mechanism; said second contact being opened when said toggle operating mechanism is moved over center as said circuit breaker is operated from an open to a closed position; said second circuit also lincluding a resistor connected in electrical series with said motor; a third normally closed contact spenta? connected in parallel with said resistor; said third contact also being opened when toggle operating mechanism Ais moved over center as said circuit breaker is operated from said open to said closed positions; said third contact being opened before said second contact is open; a third circuit connected in parallel with said first and said second circuit; said third circuit comprising a normally closed switch and a coil means connected in electrical series; said coil means being part of a polarized magnetic latch for said circuit breaker.

8. An electrical control circuit for a motor closed high `speed circuit breaker comprising a first and a lsecond circuit connected in parallel; said rst circuit including Aa normally open switch and arelay coil connected inV electrical series; said second circuit including a tir-st normally open contact and a circuit breaker closing motor connected in electrical series; saidmotor bein-g adapted to provide motive power :for physical movement of circuit breaker contacts; said. iirst contact being closed by the energization of said relay coil; a secondnormally closed contact being electrically connected between saidfswitch andsaid first contact; said rst and said second contacts comprising a by-pass circuit for said switch; said circuit breaker including a toggle operating mechanism; said secondl contact being opened when said toggle operating mechanism is moved over-center as saidr circuit breaker is operated from an open to a closed position; said second circuit also including a resistor connected in# electrical series with said motor; a third normally closed Contact connected in vparallel with said resistor; said third contact also being opened when toggle operating mechanism v is moved over-center as said circuit breaker' is operated from said open to saidclosed positions; said third contact being opened beforersaidsecond contact is open; a third circuit connected in parallel with said rst and said second circuit; said third circuit comprising a normally closed 4switch and a coil means connected in electrical series; said coil means being part of Ya polarized magnetic latch for said circuit breaker; said controlV circuit being adapted for connection to the same electrical' power source being protected lby said circuitbreaker.v

References' Cited inthe le of this patent i' UNITED STATES? PATENTS 

